The present invention relates to irregular or modified cross-sectional polyester filaments and a yarn and a fabric containing the same. More particularly, the present invention relates to irregular or modified cross-sectional polyester filaments having excellent gloss and bulkiness, a pleasant touch and a high softness, and a yarn and a fabric containing the polyester filaments and having a pleasant silky touch, a high bulkiness and a high softness.
Various means for forming a cross-sectional profile of synthetic filaments, particularly polyester filaments, into an irregular form to impart a desired hand to the filaments are known up to now. For example, it is known that a triangular cross-sectional profile can be imparted to polyester filaments to make the gloss and hand of the resultant polyester filaments close to those of silk filaments; that a multi-lobal cross-sectional profile can be imparted to synthetic filaments to increase the dry touch of the filaments; and that the cross-sectional profile of synthetic filaments can be formed in the form of a mushroom to enhance the silk-like dry touch and a silk-like creaky (scrooping) touch.
Also, it is known that a combined filament yarn can be produced from synthetic filaments having an irregular cross-sectional profile and another synthetic filaments different in shrinking property from the above-mentioned irregular cross-sectional filaments, and the resultant shrinking property-different filaments-combined yarn is used to produce a silk-like fabric having high bulkiness and softness (soft touch). However, almost all of the conventional polyester filaments having the above-mentioned silk-like hand have a hand close to that of non-wild silk filaments and polyester filaments having a hand close to that of wild silk filaments, particularly those classified into Tussah silk filaments, are rare. Particularly, the conventional silk-like synthetic filaments are definitely different in natural creaky (frictional) touch from the wild silk filaments. Also, the conventional silk-like synthetic filaments are unsatisfactory in bulkiness, softness and light weight in comparison with natural silk filaments.
Japanese Unexamined Patent Publication No. 56-20,638 discloses polyester filament yarns capable of forming a fabric having silk-like surface touch and creaky (frictional) hand. The silk-like polyester filament yarns are produced by melt-spinning a polyester composition containing an organic sulfonate salt through a plurality of spinning openings having a circular cross-sectional profile; drawing the resultant undrawn filament yarn and applying an alkali weight-reduction treatment to the drawn filaments yarn, each filament having a circular cross-sectional profile. In the silk-like polyester filament yarn, the individual filaments have a plurality of fine pores arranged along the longitudinal axes of the filaments. It is known, however, when the conventional technology is applied to the polyester filament yarn in which the individual filaments have an irregular cross-sectional profile, for example, a triangular cross-sectional profile, the resultant irregular cross-sectional polyester filament yarn are unsatisfactory in the tussah silk-like natural creaky hand, bulkiness, softness, and light weight.
On the other hand, it is known that drawn thick and thin type filaments can be obtained by drawing undrawn synthetic filaments, at a draw ratio lower than the natural draw ratio of the polyester filaments, to cause an unevenness in thickness of the resultant drawn filaments to be generated.
The surface of a fabric formed from the thick and thin type filament yarns exhibit a rough touch and an uneven appearance due to the uneven thickness of the filaments. However, when conventional synthetic filaments having a triangular or trilobal or multi-lobal cross-sectional profile are formed in a thick and thin type filament form, the resultant thick and thin type irregular cross-sectional synthetic filaments do not exhibit tussah silk-like natural creaky touch, bulkiness, softness and light weight.
Accordingly, development of polyester filaments, yarns and fabrics having tussah silk-like natural creaky touch, bulkiness, softness and light weight is strongly demanded.
An object of the present invention is to provide polyester irregular cross-sectional filaments and a yarn and a fabric containing the same, having excellent wild silk-like natural creaky touch, gloss, bulkiness, softness and light weight.
The polyester irregular cross-sectional filaments of the present invention comprises individual filaments comprising a polyester and having a transverse cross-sectional profile which has:
(A) a triangular part having a triangular form; and
(B) a flat projection part connected to an angular portion of the triangular part and extending therefrom in a flat form, and which cross-sectional profile satisfies the requirements (1) and (2) shown below:
0.7xe2x89xa6(L1/L2)xe2x89xa63.0xe2x80x83xe2x80x83(1) 
and
3.0xe2x89xa6(h2/h1)xe2x89xa610.0xe2x80x83xe2x80x83(2) 
in which requirement (1),
L1 represents a distance between a middle point of a connection line drawn between two intersecting points of a contour line of the triangular part (A) with a contour line of the flat projection part (B), and a projection end point of the flat projection part (B); and represents a distance between a middle point of the connection line between the triangular part (A) and the flat projection part (B), and a middle point of an side line of the triangular part (A) facing the connection line; and
in which requirement (2),
h1 represents a length of the connection line between the triangular part (A) and the flat projection part (B); and h2 represents a largest width of the triangular part (A) in the direction at right angles to the longitudinal direction of the flat projection part (B).
In the polyester irregular cross-sectional filaments of the present invention, the cross-sectional profile of the individual filaments preferably further satisfies the requirement (3) shown below:
2.0 less than (L1/h1)xe2x80x83xe2x80x83(3) 
In the polyester irregular cross-sectional filaments of the present invention, the triangular part (A) may have a hollow portion extending in the longitudinal direction of the filament.
In the polyester irregular cross-sectional filaments of the present invention, preferably, the polyester from which the filaments are formed is blended with an organic sulfonate metal salt represented by the general formula (I):
R SO3 Mnxe2x80x83xe2x80x83(I) 
in which formula (I), R represents a member selected from alkyl group having 3 to 30 carbon atoms, and aryl and alkylaryl groups having 7 to 40 carbon atoms; M represents a member selected from alkali metal atoms and alkaline earth metal atoms, and n represents an integer of 1 when M represents a monovalent metal atom or a number of xc2xd when M represents a divalent metal atom. In the polyester irregular cross sectional filaments of the present invention, each individual filament may comprise high thickness portions and low thickness portion alternately formed in the longitudinal direction of the filament, and the high thickness portions are preferably distributed in the number of 20/m or more.
The polyester filament yarn of the present invention comprises the polyester irregular cross-sectional filaments of the present invention as defined above.
In the polyester filament yarn of the present invention, preferably each of the polyester irregular cross-sectional filaments comprises high thickness portions and low thickness portions formed alternately in the longitudinal direction of each filament, and in the polyester filament yarn containing the thick and thin type filaments, the high thickness portions are distributed in the number of 20/m or more in the longitudinal direction of the yarn.
The combined polyester filament yarn of the present invention comprises a filament component having a lowest shrinkage in boiling water and consisting of the polyester irregular cross-sectional filaments of the present invention as defined above, and a filament component having a high shrinkage in boiling water and consisting of at least one type of polyester filaments having a higher shrinkage in boiling water than that of the polyester irregular cross-sectional filaments.
In the combined polyester filament yarn of the present invention, preferably, a difference in boiling water shrinkage between the polyester irregular cross-sectional filaments for the filament component having the lowest boiling water shrinkage, and the polyester filaments contained in the high boiling water shrinkage filament component and having a highest boiling water shrinkage, is 4 to 40%.
In the combined polyester filament yarn of the present invention, the polyester contained in the highest boiling water shrinkage polyester filaments is preferably a polyethylene trephthalate isophthalate and the content of isophtalic acid in the dicarboxylic acid component of the polyester is preferably 5 to 15 molar %.
In the combined polyester filament yarn of the present invention, preferably, the highest boiling water shrinkage polyester filaments are thick and thin filaments having large thickness portions and small thickness portions alternately distributed in the longitudinal direction of the filaments, and in the combined polyester filament yarn containing the thick and thin filaments mentioned above, the large thickness portions are distributed in the number of 20/m or more in the longitudinal direction of the yarn.
The polyester filament fabric of the present invention comprises at least one type of polyester filament yarn of the present invention as defined above, and the combined polyester filament yarn of the present invention as defined above, and has a silk-like hand.
In the polyester filament fabric of the present invention, the fabric is a woven fabric, the yarn is a twisted yarn having a twist multiplier of 2500 or more, and the twisted yarn are contained as warp yarns in the woven fabric.